1. Field of the Invention
This invention relates to a cylindrical battery assembled to have cylindrical positive and negative electrodes disposed concentrically through a separator (for example an organic electrolyte battery, alkaline zinc battery or the like) and particularly concerns a cylindrical battery structure improved for preventing capacity reduction due to self- discharge.
2. Description of the Prior Art
A reduction in capacity of this kind of battery due to self-discharge is caused, in most cases, by a phenomenon wherein one electrode swells and disintegrates partially to release a powder of the electrode material during the use of the battery and the powder comes in contact with the other electrode across the end edge of a separator interposed between both positive and negative electrodes when the battery is subjected to shock or oscillation or used upside down.
To avoid such reduction in capacity of the battery, there is made a contrivance various ways hitherto. An organic electrolyte battery is disclosed in Japanese Utility Model Publication No. 51495/1982 laid open prior to application of this invention, discloses conventional examples in FIGS. 1 to 3 and an example of the above Utility Model in FIG. 4. In FIGS. 1 to 4, 1, 1C and 1D denote cylindrical positive electrodes obtained through molding a positive electrode material, and 2A, 2B, 2C and 2D denote battery cases acting also as positive electrode terminals with the above cylindrical positive electrodes disposed inside, 3A, 3B, 3C and 3D denote cylindrical separators, 4A, 4B, 4C and 4D denote negative electrodes disposed in hollow zones of the above positive electrodes through the cylindrical separators, 5A, 5B, 5C and 5D denote negative electrode collecting cylinders, 6A, 6B, 6C and 6D denote negative electrode collectors, 7A, 7B, 7C and 7D denote battery case covers acting also as negative electrode terminals connecting electrically to the above negative electrodes through the above negative electrode collecting cylinders and negative electrode collectors 8A, 8B, 8C and 8D denote annular insulating packings for insulating the above battery cases and battery case covers.
The battery shown in FIG. 1 has a ring type insulating washer 9 disposed on an upper end of the cylindrical positive electrode 1A, which is to prevent a reduction in capacity of the battery due to self-discharge caused by the powder of the electrode material released from a positive electrode by partial disintegration of said electrode coming in contact with the negative electrode 4A side. However, when the positive electrode 1A is swelled according to discharge, the insulating washer 9 is easily pushed upward, therefore a movement of the powder cannot be prevented thoroughly. Further, since the insulating washer 9 and the insulating packing 8A are made separately, parts run many in number, which entails a complicatedness of working efficiency for assembling and a loss in volume of the insulating washer in the battery.
In the battery shown in FIG. 2, a ring type insulating washer 10 is separated upward from an upper end of the cylindrical positive electrode 1B and provided in contact with a lower surface of the insulating packing 8B. In this case, however, the insulating packing 8B cannot be fastened thoroughly, which is capable of causing a leakage. Furthermore, since the insulating washer 10 and the insulating packing 8B are made separately, parts run many in number, which entails a complicatedness of working efficiency for assembling and a loss in volume of the insulating washer in the battery as in the case of the battery given in FIG. 1.
The battery shown in FIG. 3 has the separator 3C extended as far as it comes in contact with the battery case cover 7C, however, it is difficult to keep an upper end peripheral edge of the separator 3C totally in contact with a lower surface of the battery case cover 7C, therefore the positive electrode material powder cannot be prevented thoroughly from moving to the negative electrode.
Then, the battery shown in FIG. 4 is provided with the insulating packing 8D having a collar 11, and an upper end of the separator 3D is inserted in a hole formed of a circular edge 12 of the collar 11 and smaller in diameter than the upper end outside diameter of the separator. In this case, however, the upper end of the separator 3D is constricted to produce creases on the side, which involves a difficulty in bringing into contact closely with the circular edge 12, and thus the positive electrode material powder cannot be prevented thoroughly from moving to the negative electrode, too.
This invention has been made to overcome the above problems.